The invention relates to a method of manufacturing a solar cell with a semiconductor wafer comprising a region of a first conductivity type and having on its front radiation-incident side a first major surface and on its rear side a second major surface, having a first surface layer of a second conductivity type which adjoins the first major surface and which forms with said region the active p-n junction of the solar cell, and having a second surface layer of the first conductivity type adjoining the second major surface and having a higher doping concentration than that of said region, in which in order to form the second surface layer, a first glassy layer comprising a dopant determining the first conductivity type, and a second, undoped glassy layer are successively provided on the second major surface.
Such a method is known from U.S. Pat. No. 4,158,591.
It is known that the presence of a highly doped layer on the rear side of a plate of a solar cell, which layer is of the same conductivity type as the base material of the said plate, improves the performance of said cell considerably.
However, forming the highly doped layer complicates the process of manufacturing the cell, which disadvantage is associated on the one hand with manufacturing said layer and on the other hand with the necessity of cleaning the edge faces of the wafer, so as to eliminate any risk of electric leakage between the two layers of opposite conductivity types created on the front and rear sides of the wafer.
A known method of cleaning the edge face of a semiconductor wafer consists of using plasma etching. An example of performing said technique on a wafer of a solar cell is shown in the previously mentioned U.S. Pat. No. 4,158,591. According to this example, the wafers or "slices" which have parasitic p-n junctions on their side faces are stacked and introduced into the treatment chamber of a carbon fluoride plasma reactor, where they are left for a few minutes.
Such a treatment, although comparatively short in duration, requires great care complicates the manufacturing process and increases the manufacturing cost of said cells. Other known mechanical or mechanicochemical methods might also be used to produce the same effect. However, whatever the prior art method chosen, a special treatment is still required.